1.7.5 Ensure GDM screen locks cannot be overridden

Information

GNOME Desktop Manager can lock down specific settings by using the lockdown mode in dconf to prevent users from changing specific settings.

To lock down a dconf key or subpath, create a locks subdirectory in the keyfile directory. The files inside this directory contain a list of keys or subpaths to lock. Just as with the keyfiles, you may add any number of files to this directory.

Setting a lock-out value reduces the window of opportunity for unauthorized user access to another user's session that has been left unattended.

Without locking down the system settings, user settings take precedence over the system settings.

Solution

- To prevent the user from overriding these settings, create the file /etc/dconf/db/local.d/locks/00-screensaver with the following content:

# Lock desktop screensaver settings
/org/gnome/desktop/session/idle-delay
/org/gnome/desktop/screensaver/lock-delay <xhtml:ol start="2"> - Update the system databases:

# dconf update

Note:

- A user profile must exist in order to apply locks.
- Users must log out and back in again before the system-wide settings take effect.

See Also

https://workbench.cisecurity.org/benchmarks/18960